Optical sensor including disposable and reusable elements

ABSTRACT

An embodiment of the present disclosure provides a noninvasive optical sensor or probe including disposable and reusable components. The assembly of the disposable and reusable components is straightforward, along with the disassembly thereof. During application to a measurement site, the assembled sensor is advantageously secured together while the componentry is advantageously properly positioned.

PRIORITY CLAIM

This application claims priority benefit under 35 U.S.C. § 119(e) fromU.S. Provisional Application No. 60/740,541, filed Nov. 29, 2005,entitled “Optical Sensor Including Disposable and Reusable Elements.”The present application incorporates the foregoing disclosure herein byreference.

REFERENCE TO RELATED APPLICATIONS

This application also relates to U.S. Pat. No. 6,920,345, filed on Jan.24, 2003 and issued on Jul. 19, 2005, entitled “Optical Sensor IncludingDisposable And Reusable Elements.” The present application alsoincorporates the foregoing disclosure herein by reference.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to noninvasive optical sensors capable ofdetecting light attenuated by body tissue. More specifically, thedisclosure relates to the combination of reusable and disposablecomponents of such sensors.

2. Description of the Related Art

Early detection of low blood oxygen is important in a wide range ofapplications, including patient monitoring, the fitness industry, homecare and the like. Noninvasive oximetry was developed to study and tomeasure, among other things, the oxygen status of blood. Pulseoximetry—a noninvasive, widely accepted form of oximetry—relies on asensor attached externally to a patient to output signals indicative ofvarious physiological parameters, such as a patient's blood oxygensaturation.

A pulse oximeter sensor generally includes one or more energy emissiondevices, such as specific wavelength emitting LEDs, and one or moreenergy detection devices. The sensor is generally attached to ameasurement site such as a patient's finger, ear, ankle, or the like,using an attachment mechanism such as a disposable tape, reusablehousing, a plastic or hook-and-loop fastening strap, or the like. Theattachment mechanism positions the emitters and detector proximal to themeasurement site such that the emitters project energy into the bloodvessels and capillaries of the measurement site, which in turn attenuatethe energy. The detector then detects that attenuated energy. Thedetector communicates at least one signal indicative of the detectedattenuated energy to a signal processing device such as an oximeter. Theoximeter generally calculates, among other things, one or morephysiological parameters of the measurement site.

Noninvasive oximetry sensors can be disposable, reusable, or somecombination thereof. Reusable sensors offer advantages of superior costsavings. However, reusable sensors are often available in a limitednumber of sizes even though patient measurement sites, such as fingersor toes, can have a much larger size distribution. Therefore, sometimesreusable sensors do not readily conform to each patient's measurementsite. Disposable sensors on the other hand offer superior conformance tothe measurement area. However, disposable sensors are generally morecostly due to limited use of the relatively expensive sensor componentswhich could otherwise last for repeated uses.

Faced with the drawbacks of reusable and disposable sensors,manufacturers began designing a number of middle-ground sensors. Forexample, some manufacturers offer a reusable detector portion thatcouples to a disposable emitter portion. After a single use, thedisposable emitter portion is detached from the reusable detectorportion and discarded. While this design reuses some of the expensiveelectronic components, obviously others are still discarded.

Another example of a middle-ground sensor includes a reusable “Y” typesensor, where a reusable emitter portion connects to one branch of the“Y” while a reusable detector portion connects to the other branch. Adisposable tape positions the two branches on a measurement site. Inthis design, the electronics are reusable; however, the multiple wirestend to be somewhat difficult to properly attach, especially with amoving patient.

Other examples of middle-ground sensors include a disposable tapesandwich where a reusable flexible circuit housing an emitter portionand a detector portion, are “sandwiched” between adhesive layers.Separation of such disposable tape sandwiches can be cumbersome. In yetanother example of a middle-ground sensor, the Assignee of the presentapplication disclosed a reusable flexible circuit that is snapped into adisposable tape. In an embodiment of that disclosure, small pegs on theflexible circuit snap into mechanically mating elements on thedisposable tape. Grooves allow some longitudinal travel between thereusable portion and the disposable portion, thereby allowing for someself adjustment between components to account for differences in radialattachment requirements.

SUMMARY OF THE DISCLOSURE

However, even with the advances discussed in the foregoing, therecontinues to be a need for a commercially viable, straightforward,middle-ground solution that offers reusability of expensive electroniccomponents while maintaining some of the advantages of disposableattachment.

Accordingly, one aspect of an embodiment of the present disclosure is toprovide a sensor having reusable and disposable components. In anembodiment, the sensor advantageously includes a disposable componentstructured to provide a locking feature capable of reducing a chancethat the disposable and reusable components can separate when attachedor otherwise in close proximity to the body. In an embodiment, a lockingmechanism takes advantage of longitudinal displacement and engages whenthe reusable and disposable portions of the sensor are curved around themeasurement site (such as a finger). Separation of the reusable portionfrom the disposable portion is then advantageously complicated until thesensor is removed from the patient and the displacement is reversed.

A further aspect of an embodiment of this disclosure is that the tip ofthe reusable sensor component slides angularly into the front housingcomponent on the disposable portion before sitting flat in a slot orguide. The slot or guide includes a rubber stop that in an embodimentadvantageously provides a fluid-tight or at least fluid resistantcontact.

In a further embodiment, a memory device or information element isprovided as part of the disposable housing. An electrical contact ismade between the memory device and the reusable components to, forexample, ensure quality control in the disposable housing, provideinformation to the patient monitor about the type of sensor, type ofpatient, type of attachment mechanism or attachment position,information about operating characteristics of the sensor, productmanufacture or sale history, distributor history, amount of use,combinations of the same or the like.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the disclosure have been described herein. Ofcourse, it is to be understood that not necessarily all such aspects,advantages or features will be embodied in any particular embodiment ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings and the associated descriptions are provided toillustrate embodiments of the present disclosure and do not limit thescope of the claims.

FIG. 1 illustrates an exemplary block diagram of an oximeter systemincluding a sensor and a monitoring instrument, according to embodimentsof the disclosure.

FIG. 2 illustrates a perspective view of the sensor of FIG. 1, wherereusable and disposable components of the sensor are separated accordingto an embodiment of the disclosure.

FIGS. 3A-3B illustrate perspective views of the sensor of FIG. 2, wherethe components are connected in an assembly/disassembly position,according to an embodiment of the disclosure.

FIG. 4 illustrates a perspective side view of the sensor of FIG. 2,where the components are in an attached position, according to anembodiment of the disclosure.

FIG. 5A-5B illustrate top and bottom perspective views of a detectorcasing or housing of the reusable component, according to an embodimentof the disclosure.

FIG. 6A-6B illustrate top and bottom perspective views of an emittercasing or housing of the reusable component, according to an embodimentof the disclosure.

FIG. 7 illustrates a perspective view of a front holding clip of thedisposable component, the clip being capable of mechanically mating withthe detector casing of FIG. 5, according to an embodiment of thedisclosure.

FIG. 8 illustrates a perspective view of the assembly/disassembly clipof the disposable component, the clip being capable of mechanicallymating with the emitter casing of FIG. 6, according to an embodiment ofthe disclosure.

FIG. 9 illustrates a top planar view of the disposable componentincluding the front holding clip and the assembly/disassembly clip ofFIGS. 7-8, according to an embodiment of the disclosure.

FIG. 10A illustrates an exploded view of the disposable component,according to an embodiment of the disclosure.

FIG. 10B illustrates an exploded view of the reusable component,according to an embodiment of the disclosure.

FIG. 11 illustrates top planar and side views of component placement ofconventional sensors.

FIG. 12 illustrates top planar and side views of component placementaccording to an embodiment of the disclosure.

FIG. 13 illustrates a top down planar view of a disposable sensor,according to an embodiment of the disclosure.

DETAILED DESCRIPTION

An embodiment of the present disclosure is a sensor with a reusablecomponent and a disposable component. The reusable component generallyincludes reusable expensive electronic components of a sensor,including, for example, the emitters and detector. In an embodiment, theemitters and the detector are located in respective casings connected bya short flexible circuit. In an embodiment, a disposable componentincludes mechanically matable portions adapted to mechanically mate withthe casings of the reusable component. In an embodiment, the casings ofthe reusable component mate with the disposable component in a mannerthat provides an assembly/disassembly state, and an attached state.During the assembly/disassembly state, a caregiver can readily andstraightforwardly assemble the sensor by aligning the casings on thereusable component and the mechanical housings of the disposablecomponent and snapping them together. In an embodiment, the alignment isgenerally vertical in nature and the snapping occurs by lightly pressingon the components while on a flat surface or supported from underneathby, for example, the hand of the assembler. Each detector housinggenerally vertically accepts the casings; however, one of the casings,such as, for example, the forward housing or clip accepts the casing insuch a way as to keep the forward casing generally immobile.

Disassembly is equally as straightforward, as the caregiver mayadvantageously lift on the reusable component wire, and the rearwardcasing extracts from the mechanically mated housing of the disposableelement. Continual lifting then similarly extracts the forward casingfrom the mechanically mated housing of the disposable element. In anembodiment, the flexible circuit between the forward and rearward casingmay be reinforced in order to withstand multiple disassembly stresses orforces occurring from the lifting of the reusable wire. In anembodiment, pressing the disposable portion onto a flat surface whilelifting the reusable portion aids in the disassembly process.

The disposable portion includes structures designed to attach the sensorto a measurement site. In an embodiment, the disposable portioncomprises a flexible tape having an adhesive side capable of removablyadhering to the measurement site. In an embodiment where the disposableportion wraps around a measurement site, the act of bending the flexiblecircuit advantageously causes the assembly/disassembly clip to recessinto the mechanically mated portion of the disposable housing, therebyreducing the likelihood of disassembly during application to ameasurement site. In an embodiment, the sensor components are lockedtogether through the longitudinal displacement of the clip with respectto the disposable housing. In such an embodiment, a stop diminishes thecapacity of the clip to move vertically, thereby locking it into place.In this embodiment, removing the adhesive from the measurement site andstraightening the sensor components unlocks the reusable and disposablecomponents.

In an embodiment, assembly also necessarily electrically connectselectronic components of the disposable portion with those of thereusable portion. In an embodiment, then disposable portion includes aninformation element or memory device, such as, for example, a resistor,a single wire addressable memory device, such as those EPROMs or EEPROMscommercially available from Dallas Semiconductor, other memory orprocessing devices, combinations of the same, or the like. Theinformation element may include data accessibly by an attached patientmonitor to accomplish quality control, monitor configuration, sensor usemonitoring, combinations of the same, or the like.

Still other advantages of embodiments of the present disclosure includeproportionally positioning of the mechanically mating housings toprovide for optical alignment between the emitters and detector.Moreover, in embodiments including the disposable tape, the tape mayadvantageously be scored to assist the caregiver in proper alignmentwith the body tissue at the measurement site.

To facilitate a complete understanding of the disclosure, the remainderof the detailed description describes the disclosure with reference tothe drawings. Corresponding parts refer to corresponding elements andthe leading digit indicates the figure in which that element firstappears.

General Design

FIG. 1 presents an exemplary block diagram of the components generallyfound in an oximeter sensor, according to an embodiment of theinvention. For example, FIG. 1 shows as oximeter system 100 includingsensor 102, cable 170, and monitor 172. The sensor 102 includes one ormore emitters 174 for irradiating body tissue with light, and one ormore detectors 176 capable of detecting the light after attenuation bythe tissue. The sensor 102 also includes an information element 136 suchas an EPROM. The sensor 102 also includes a plurality of conductorscommunicating signals; including emitter drive signal conductors 180,detector composite signal conductors 182, and EPROM conductors 184.According to an embodiment, the sensor conductors 180, 182, 184communicate their signals to and from the monitor 172 through cable 170.

Although disclosed with reference to the cable 170, a skilled artisanwill recognize from the disclosure herein that the communication to andfrom the sensor 106 may advantageously include a wide variety of cables,cable designs, public or private communication networks or computingsystems, wired or wireless communications, combinations of the same, orthe like.

The information element 136 may comprise an EPROM, an EEPROM,combinations of the same, or the like. In general, the informationelement 136 may include a read-only device or a read and write device.The information element may advantageously also comprise a resistor, anactive network, or any combination of the foregoing. The remainder ofthe present disclosure will refer to such possibilities as simply aninformation element for ease of disclosure.

The information element 136 may advantageously store some or all of awide variety of data and information, including, for example,information on the type or operation of the sensor 104, type of patientor body tissue, buyer or manufacturer information, sensorcharacteristics including the number of wavelengths capable of beingemitted, emitter specifications, emitter drive requirements,demodulation data, calculation mode data, calibration data, softwaresuch as scripts, executable code, or the like, sensor electronicelements, sensor life data indicating whether some or all sensorcomponents have expired and should be replaced, encryption information,or monitor or algorithm upgrade instructions or data. The informationelement 136 may advantageously configure or activate the monitor,monitor algorithms, monitor functionality, or the like based on some orall of the foregoing information. For example, without authorized dataaccessibly on the information element 136, quality control functions mayinhibit functionality of the monitor. Likewise, particular data mayactivate certain functions while keeping others inactive. For example,the data may indicate a number of emitter wavelengths available, whichin turn may dictate the number and/or type of physiological parametersthat can be monitored or calculated.

FIG. 1 also shows the monitor 172 comprising one or more processingboards 186 communicating with one or more host instruments 188.According to an embodiment, the board 186 comprises processing circuitryarranged on one or more printed circuit boards capable of beinginstalled in specialized monitoring equipment or distributed as an OEMcomponent for a wide variety of patient monitoring equipment. As shownin FIG. 1, the board 186 includes a front end signal conditioner 190, asensor controller 194, a digital signal processor or microcontroller192, and a memory reader 1102. In an embodiment, the processor 192instructs the sensor controller 194 to output one or more drive signalscapable of causing the emitters 174 to activate. The front end 190receives detector output indicating detection of light from the emitters174 attenuated by body tissue of the measurement site. The front end 190conditions the signal and outputs the signal and/or signal data to theprocessor 192. The processor 192 executes calculations adapted todetermine values and/or indications or physiological parameters, trendsof the parameters, alarms based on the parameters or the trends orcombinations of trends and/or parameters, or the like. In addition, thereader 1102 is capable of retrieving information stored on informationelement 136. The reader 1102 or the processor 192 may advantageouslydecrypt such information to the extent desired.

In an embodiment, the host instrument 188, communicates with theprocessor 192 to receive signals indicative of the physiologicalparameter information calculated by the processor 192. The hostinstrument preferably includes one or more display devices 196 capableof providing indicia representative of the calculated physiologicalparameters of the tissue at the measurement site. Such display devices196 may be controlled by a monitor controller 198 that accepts signalsfrom processor 192. In an embodiment, monitor controller 198 may alsoaccept signals from user interface 1100. Such signals may be indicativeof various display options for configuring the output to display 196. Inan embodiment, the host instrument 188 may advantageously be capable ofdisplaying one or more of a pulse rate, plethysmograph data, perfusionquality, signal or measurement quality, values of blood constituents inbody tissue, including for example, SpCO, functional or fractional SpO₂,or the like. In other embodiments, the host instrument 188 is capable ofdisplaying values for one or more of SpMet, HbO₂, Hb, HbCO, HbMet, Hct,blood glucose, bilirubin, or the like. In still additional embodiments,the host instrument 188 is capable of displaying trending data for oneor more of the foregoing measured or determined data. Moreover anartisan will realize from the disclosure herein many display options forthe data are available.

In an embodiment, the host instrument 188 includes audio or visualalarms that alert caregivers that one or more physiological parametersare falling below predetermined safe thresholds, and may includeindications of the confidence a caregiver should have in the displayeddata. In further embodiment, the host instrument 188 may advantageouslyinclude circuitry capable of determining the expiration or overuse ofcomponents of the sensor 102, including for example, reusable elements,disposable elements, or combinations of the same.

Although disclosed with reference to particular embodiment, an artisanwill recognize from the disclosure herein many variations of theinstrument 172. For example, in a broad sense, the instrument 172accepts data from the sensor 102, determines values for one or moreparameters, trends, alarms or the like, and outputs them to an interfacesuch as a display.

Sensor Configuration

FIG. 2 illustrates an embodiment of sensor 102, having reusablecomponent 204 and disposable component 206. The components are showndetached. FIG. 3 shows a very similar perspective drawing, but withreusable component 204 and disposable component 206 in their attached,in their assembled state. Returning to FIG. 2, the reusable component204 comprises an emitter casing 208, a detector casing 210, and aflexible circuit 212. The emitter casing 208 comprises one or moreemission devices operable to emit light at multiple wavelengths, such asred and infrared. Detector casing 210 houses one or more detectors, suchas a photodiode detector. In an embodiment, a flexible circuit connectsthe emitter casing 208 and detector casing 210. In a preferredembodiment, the flexible circuit is housed in a protective cover andextends beyond the emitter casing 208. An artisan will understand fromthe disclosure herein that the emitter and detector electricalcomponents may advantageously be housed in the casings disclosed orsimply reversed from the foregoing disclosure. In an embodiment, theflexible circuit 212 and/or cabling extends significantly beyond thecasings to advantageously remove any cable attachment mechanisms fromthe proximity of the tissue site.

FIG. 2 also shows the disposable component 206 including a base 214, anassembly/disassembly clip 216 and a front holding clip 218, the clipseach adapted to accept the emitter casing 208 and detector casing 210,respectively. In the preferred embodiment, front holding clip 218includes a front stop 220. Front stop 220 is advantageous for a numberof reasons. It helps reduce the likelihood that the reusable component102, and in particular detector casing 210, will slide forward in thefront holding clip 218 during assembly or use. In addition, in anembodiment where the stop 220 comprises rubber or other liquid resistantmaterial, the stop 220 provides a liquid resistant connection betweenthe detector casing 210 and front holding clip 218, reducing thelikelihood of sensor contamination and electrical shorts. Rubber or asimilar material may be used in an embodiment to compose such a frontstop 220.

FIG. 3A shows detector casing 210 clipped or snapped into front holdingclip 218 with a tip of the casing slid below a portion of the front stop220. This allows the front stop 220 to reduce not only horizontalmovement of the detector casing 210, but also helps reduce verticalrelease of the detector casing unless pulled from, for example, thecable. FIG. 3 also shows the front stop 220 with a generally roundedshape providing a relatively soft material with few, if any, sharpedges. Such an embodiment advantageously reduces damage to a patient orthe sensor if the patient tries to scratch body tissue using the edgesof the assembled sensor, or if the sensor is dropped, banged againstsomething while worn, or the like. This is particularly useful when usedwith burn victims or other patients whose skin may damage easily.

FIG. 3B highlights the ease of assembly. The disposable portion 206 isset on a surface or held in the one hand. The caregiver then aligns afront tip of casing 210 and guides it into front holding clip 218. Thisis more a vertical alignment with the front tip snapping below stop 220.The casing 210 including rounded wings 531 (FIG. 5) that mechanicallyassociate with rounded side walls 739 (FIG. 7). These mechanicalstructures allow the tip of casing 210 to slide below stop 220, and snapdown into place. Once casing 210 is in place, casing 208 alignsvertically and simply slides down, with tabs 262 (FIG. 6) locatedsliding into slots 222 (FIG. 8) on either side of assembly/disassemblyclip 216. In an embodiment, the flexible circuit portion 212 between thecasings 208 and 210 may bulge slightly.

FIG. 3B shows the emitter casing 208 after it has been slid ontoassembly/disassembly clip 216. With the reusable sensor component 204and the disposable sensor component 206 in a generally flat position,the emitter casing 208 remains vertically mobile in slots 222 ofassembly/disassembly clip 216. When the sensor 102 is wrapped around ameasurement site 426, such as a finger, as shown in FIG. 4, emittercasing 208 slides forward in assembly/disassembly clip 216 due to thetension from flexible circuit 212 and detector casing 210 beingsubstantially immobile in front holding clip 218. Tabs 262 (FIG. 6)slide away from slots 222 (FIG. 8) and under holding elements 224 (FIG.8). Holding elements 224 prevent emitter casing 208 from movingvertically or further forward by restricting tabs 262. As stated before,the tension from flexible circuit 212 when it is wrapped around ameasurement site 426 prevents the emitter casing 208 from movinghorizontally backwards. The immobility of casing 210, combined with thetabs 262 sliding out of alignment with slots 222, effectively secure thereusable sensor component 204 with respect to disposable component 206,with the emitters appropriately position with respect to the detector.Thus, realignment through release of tension, i.e., removing the sensorfrom an attachment site and straightening it out, ensure straightforwarddisassembly of the sensor components. Although shown using tabs 262 andslots 222, a skilled artisan will recognize from the disclosure herein awide variety of mechanical mechanisms that ensure reliable attachabilitywhen the sensor is applied to the tissue site and straightforwardassembly/disassembly when the sensor is removed. For example, one ormore detents that snap closed beyond a catch and are released throughpinching could be used to secure the reusable portion 104 to thedisposable portion 106.

As alluded to previously, FIG. 4 depicts sensor 102 as would be seenwhen in use on a measurement site 426. In this case, the measurementsite is a finger, but other sites such as a toe, ear, wrist or ankle mayalso work. Disposable component 206 and reusable component 204 areattached, and reusable component 204 is in the assembled and attachedposition. Longitudinal tension on the flexible circuit 212 from thediffering radius between the tape and the circuit has pulled the emittercasing 208 forward, placing tabs 262 under holding elements 224. FIG. 4shows that, in an embodiment, emitter casing 208 is rearward withrespect to assembly/disassembly clip 216 when in the unattached position(FIG. 3B), but the front of emitter casing 208 is forward and in anembodiment, generally flush with assembly/disassembly clip 216 when inthe attached position (FIG. 4).

FIGS. 5A-5B show close up top and bottom perspective views of anembodiment of the detector casing 210. Electrical contact acceptors 528are shown as insets on the sides of detector casing 210. In anembodiment, electrical contact acceptors 528 are located on either sideof the detector casing 210 and include conductive material that would beconnected to a wire in flexible circuit 212. Buttons 530 found on eitherside of the detector casing 210 are, in the preferred embodiment,generally hemispherical protrusions adapted to sit in depressions 738found on front holding clip 218 (see FIG. 7).

FIG. 7 shows a close up perspective view of an embodiment of the frontholding clip 218, again to show detail less easily seen in smallerfigures. While most of the front sensor clip 218 may be made of plasticor some other rigid material, the preferred embodiment has front stop220 made of rubber as has been discussed. Opening 732 is also shown hereand may be a hole through front holding clip 218 or may just be of agenerally transparent material that will allow light from the LEDs toenter the tissue at the measurement site and allow light energy to beread by the photodiode. Having window 732 be transparent material willallow the sensor to obtain readings while keeping the LEDs andphotodiode from becoming contaminated. Other optical filters or the likecould also be housed in window 732.

Located inside front stop 220 are conducting prongs 734. Conductingprongs 734 are adapted to fit into electrical contact acceptors 528. Inan embodiment, the conducting prongs 734 close the circuit with theinformation element 136. When the detector casing 210 clips into frontholding clip 218, the conducting prongs 734 slide into electricalcontact with acceptors 528. The completed circuit allows the sensor 102,and in turn an oximeter, to communicate with information element 136.Depressions 738 are located on the interior of front holding clip 218.They are preferably generally hemispherical depressions similar in sizeto buttons 530, so as to accept buttons 530, and hold detector casing210 in a substantially immobile position relative to front holding clip218. Thus, a straightforward snap-in snap-out friction fit isaccomplished using buttons 520 and depressions 738.

FIGS. 6A-6B show close up top and bottom perspective views of emittercasing 208. Rear pegs 660 are located on either side of emitter casing208. When tabs 262 slide down slots 222 of assembly/disassembly clip216, rear alignment pegs 660 slide down behind assembly/disassembly clip216. Rear pegs 660 provide further restriction from forward movement,and structural support integrity, once emitter casing 208 has slid intoa locking position by hitting rear stops 840 in assembly/disassemblyclip 216 (See FIG. 8).

FIG. 8 illustrates a close-up perspective view of a assembly/disassemblyclip 216 according to the preferred embodiment. As discussed emittercasing 208, slides down into assembly/disassembly clip 216 with tabs 262passing through slots 222 and rear pegs 660 passing behindassembly/disassembly clip 216. As emitter casing 208 slides forward dueto pull from application to a user, tabs 262 generally restrictover-forward movement or any vertical movement by abutting holdingelements 224. Rear pegs 660 also generally abut rear stops 840.Assembly/disassembly clip 216 also has a window 842 that issubstantially similar to window 732 on the front holding clip 218.

FIG. 9 shows a top down view of the disposable sensor element. As shownin FIG. 9, the assembly/disassembly clip 216 and the slots 222 thatallow vertical entry of the tabs 262 and the emitter casing 208.Moreover, FIG. 9 shows windows 842 and 732 in assembly/disassembly clip216 and front holding clip 218, respectively. FIG. 9 also shows windows944 and 946. Windows 944, 946 are included in the base 214. Like theopenings 732, 842, windows 944, 946 may either be holes through base214, or they may be of a material allowing free light transmission.Windows 944, 946 generally align with openings 732 and 842 to provideoptical access to the measurement site for the emitters and detectors ofthe sensor. FIG. 9 also shows the contact prongs 734 on the insides offront holding clip 218. The contact prongs 734 connect the reusablesensor component 204 to information element 136, which may be variouslyutilized such as for storing information relating to the sensor'smanufacturer or the like.

Manufacture

FIG. 10A illustrates an exploded view of an embodiment of disposablesensor component 206. As shown in FIG. 10A, disposable sensor component206 comprises a plurality of layers. For example, disposable sensorcomponent 206 includes a base tape 1038. This base tape 1038 ispreferably transparent polyethylene approximately 0.001 inches thick.Such material can be purchased from various sources, such as ProductNumber 3044 from Avery Dennison Medical of 7100 Lindsey Dr., Mentor,Ohio, 44060. As with all dimension recitations herein, an artisan willrecognize from the disclosure herein that the dimensions of a particularlayer may advantageously be redesigned according to various designdesires or needs, and layers may be added or combined without departingfrom the scope of the present disclosure.

A second layer comprises a tape or web layer 1040. This layer ispreferably white polypropylene also approximately 0.001 inches thick.One potential source for this material is Scapa North America, 540 NorthOak Street, Inglewood, Calif., 90302, specifically product number P-341.Tape layer 1040 also has windows 1054 that allow light energy emanatingfrom the sensor emitters to pass through this layer to the measurementsite 426 and also allows the light to pass through to the detector. Thewindows 1054 may be holes, transparent material, optical filters, or thelike. In the preferred embodiment, base tape 1038 does not have windows1054. Base tape 1038 is preferably generally clear as discussed above.This allows light to pass through the tape from the sensor, while alsogenerally reducing contamination of the sensor components. Disposablecomponent 206 also includes clip 218 and assembly/disassembly clip 216.In an embodiment, information element 136 resides in a depression orslot within clip 218, preferably affixed in place by adhesives and/ormechanical structure. In an embodiment, a polyester film layer 1042sandwiches the clips 216, 218 in place. In an embodiment the polyesterfilm layer 1042 is generally clear and approximately 0.003 inches thick.Polyester film layer 1042 also includes slots 1044 to allow the verticalelements of assembly/disassembly clip 216 and front holding clip 218 toprotrude therefrom and to allow polyester film layer 1042 to sitrelatively flatly against the bases of assembly/disassembly clip 216 andfront holding clip 218. Front stop 220 may be connected to the verticalelements of front holding clip 218 with polyester film layer 1042therebetween.

The disposable portion 204 also includes light-blocking layer 1046,preferably made of metalized polypropylene approximately 0.002 inchesthick. This is a commercially available product available, for example,as Bioflex™ RX48P. Light-blocking layer 1046 has cut-outs 1048 adaptedto accept assembly/disassembly clip 216 and front holding clip 218.Light-blocking layer 1046 increases the likelihood of accurate readingsby preventing the penetration to the measurement site of any ambientlight energy (light blocking) and the acquisition of nonattenuated lightfrom the emitters (light piping). Above light blocking layer 1046 is anopaque branding layer 1047 also having cut-outs 1048. This brandinglayer may advantageously comprise manufacturer's logos, instructions orother markings. Disposable sensor component 206 also comprises face tape1050. This face tape 1050 is preferably a clear film approximately 0.003inches thick and may be obtained commercially through companies such as3M (product number 1527ENP), located in St. Paul, Minn., 55144. Facetape 1050 has cut-outs 1052 adapted to accept assembly/disassembly clip216 and front holding clip 218.

Additional Advantages

FIG. 11 illustrates a disposable sensor highlighting issues relating tosensor positioning. Generally, when applying the sensor of FIG. 11, acaregivers will split the center portion between the emitter anddetector around, for example, a finger or toe. This may not be ideal,because as shown, it places the emitter 174 and detector 176 in aposition where the optical alignment may be slightly or significantlyoff.

FIG. 12 illustrates an embodiment of the disposable component 206including scoring line 1258. Scoring line 1258 is particularlyadvantageous, because it aids in quick and proper placement of thesensor on a measurement site 426. Scoring line 1258 lines up with thetip of a fingernail or toenail in at least some embodiments using thosebody parts as the measurement site. FIG. 12 also illustrates thedisposable component 206 where the distance between the windows 944, 946is purposefully off center. For example, in an embodiment, the clips 216and 218 will position the sensor components off center by an approximate40%-60% split. A scoring line 1258 preferably marks this split, havingabout 40% of the distance from window 946 to window 944 as the distancebetween window 946 and the scoring line 1258. This leaves the remainingapproximately 60% of the distance between the two windows 944, 946 asthe distance between scoring line 1258 and window 944.

Scoring line 1258 preferably lines up with the tip of the nail. Theapproximately 40% distance sits atop a measurement site 426, such as thefigure shown in a generally flat configuration. The remainingapproximately 60% of the distance, that from the scoring line 1258 towindow 944, curves around the tip of the measurement site 426 and restson the underside of the measurement site. This allows windows 944,946—and thus in turn detector 176 and emitter 174—to optically alignacross measurement site 426. Scoring line 1258 aids in providing a quickand yet typically more precise guide in placing a sensor on ameasurement site 426 than previously disclosed sensors. While disclosedwith reference to a 40%-60% split, the off center positioning mayadvantageously comprise a range from an about 35%—about 65% split to anabout 45%—about 55% split. In a more preferred embodiment, window 944 toscoring line 1258 would comprise a distance of between about 37.5% andabout 42.5% of the total distance between window 944 and 946. In themost preferred embodiment, the distance between window 944 and scoringline 1258 would be approximately 40% of the total distance betweenwindow 944 and window 946, as is illustrated in FIG. 12. With a general40%-60% split in this manner, the emitter and detector should generallyalign for optimal emission and detection of energy through themeasurement site.

FIG. 13 illustrates a disposable sensor containing many of the featuresdiscussed in this disclosure. Based on the disclosure herein, one ofordinary skill in the art may advantageously fix the componentsdiscussed herein to form a disposable sensor without moving beyond thescope of the present disclosure.

Although the sensor disclosed herein with reference to preferredembodiments, the disclosure is not intended to be limited thereby.Rather, a skilled artisan will recognize from the disclosure herein awide number of alternatives for the sensor. For example, the emitter anddetector locations may be in the opposite housings from what wasdiscussed here. It is also possible that the assembly/disassembly clipand sensor clip would be reversed in relation to the casings into whichthey clip. Additionally, other combinations, omissions, substitutionsand modifications will be apparent to the skilled artisan in view of thedisclosure herein. Accordingly, the present disclosure is not intendedto be limited by the reaction of the preferred embodiments, but is to bedefined by reference to the appended claims.

Additionally, all publications, patents, and patent applicationsmentioned in this specification are herein incorporated by reference tothe same extent as if each individual publication, patent, or patentapplication was specifically and individually indicated to beincorporated by reference.

1. A noninvasive optical sensor having a reusable portion and adisposable portion and being capable of outputting a signal indicativeof light attenuated by body tissue usable to determine one or morephysiological characteristics of the body tissue, the optical sensorcomprising: a reusable component including at least one energy emitterand a detector capable of detecting energy attenuated by body tissue andcapable of outputting a signal usable to determine one or morephysiological characteristics of the body tissue, the at least oneenergy emitter being housed in a first casing and the detector beinghoused in a second casing, wherein the first and second casings areconnected by a flexible connector; and a disposable component includinga first clip mechanically matable with the first casing and a secondclip mechanically matable with the second casing, wherein at least oneof the first and second clips mechanically mates in a substantiallyfixed manner with respect to the appropriate casing while the other ofthe first and second clips mechanically mates in a vertically andhorizontally open manner with respect to the appropriate casing, whereinapplication of the disposable component to the body tissue moves thevertically and horizontally open mating to be at least substantiallyvertically fixed.
 2. The optical sensor of claim 1, wherein removal ofthe disposable component from the body tissue moves the substantiallyvertically fixed mating back to being vertically and horizontally open,thereby permitting straightforward separation of the disposable and theremovable components.
 3. The optical sensor of claim 1, wherein thedisposable component comprises an information element, and whereinassembly of the reusable and disposable components creates an electricalconnection between the information element and conductors of thereusable element.
 4. The optical sensor of claim 1, wherein thedisposable component positions the first and second casings off centersuch that distance from a center to one of the first and second casingsranges from about 35% to about 45% of the distance.
 5. The opticalsensor of claim 1, wherein the disposable component positions the firstand second casings off center such that distance from a center to one ofthe first and second casings ranges from about 65% to about 55% of thedistance.
 6. A reusable element of a noninvasive optical sensor, thereusable element comprising: at least one energy emitter; a detectorcapable of detecting energy attenuated by body tissue and capable ofoutputting a signal usable to determine one or more physiologicalcharacteristics of the body tissue; a first casing housing one of the atleast one energy emitter and the detector, the first casing including aplurality of tabs capable of sliding vertically within a slot in anappropriate disposable attachment upon assembly with the disposableattachment and sliding horizontally along a groove in the disposableattachment during attachment thereof to the body tissue, therebysubstantially vertically fixing the first casing with respect to thedisposable attachment; a second casing housing the other of the at leastone energy emitter and the detector, the second casing including anelectrical contact capable of electrically communicating with electricalcomponents in the disposable attachment and including a plurality ofmechanical structures capable of substantially fixing the second casingwith respect to the disposable attachment upon assembly; and areinforced flexible connector connecting the first casing to the secondcasing.
 7. A disposable element of a noninvasive optical sensor, thedisposable element comprising: a first receptacle capable accepting afirst housing of a first electronic element of a reusable component ofthe noninvasive optical sensor, the first receptacle comprising verticaland horizontal slots for vertically receiving tabs of said first housingupon assembly and horizontally receiving the tabs upon application tobody tissue; a second receptacle capable of accepting a second housingof a second electronic element of a reusable component, at least one ofthe first and second electronic elements comprising a detector capableof detecting light attenuated by body tissue, the second receptaclecomprising an electrical contact and a front stop comprising a fluidresistance material, wherein the electrical contact is at leastpartially protected by the front stop from fluid contamination when thereusable component is assembled with the disposable element; and aninformation element electrically connected to the electrical contact. 8.The disposable element of claim 7, wherein the disposable element isscored.
 9. A method of assembling a noninvasive optical sensor, themethod comprising: providing a reusable portion including housings forelectronic elements; providing a disposable portion including clips forreceiving said housings, wherein a first housing is substantiallyvertically received and when received, substantially fixes said firsthousing with respect to said disposable portion, and wherein a secondhousing is substantially vertically received; snapping said firsthousing into one of said clips on said disposable portion, therebycreating an electrical contact between conductors of said reusableportion and an information element of said disposable portion; andsliding said second housing into another of said clips on saiddisposable portion, to form an assembled noninvasive optical sensor. 10.The method of claim 9, further comprising attaching the assembled sensorto a measurement site.